body{
    background-image: url(../img/fondo.png); 
}
#centrar{
    position: absolute;
    top: 50%;
    left: 60%;
    margin-top: -210px;
    margin-left: -320px;   
}

.ui-icon.llave{
    background-image: url(../img/login.png);
    margin-right: 4px;       
}

.ui-icon.inicio{
    background-image: url(../img/inicio.png);
    margin-right: 4px;       
}
